Doesn't libigl use Eigen for matrices? Eigen is a full-featured matrix library with a pretty decent API. If you just need a 4x4 grid of numbers, then you don't

Doesn't libigl use Eigen for matrices? Eigen is a full-featured matrix library with a pretty decent API. If you just need a 4x4 grid of numbers, then you don't really need a library, sure. But once you need to do matrix arithmetic, basic linear algebra, various forms of indexing, mixing matrices of different types (e.g. float/double/int/etc), things get complicated, fast. A complex library like igl needs all this and more. I'm guessing this is why there's so many matrix libraries - everyone prefers rolling their own, after all, how hard can it be? (I'm guilty of this, so I'd know. But I reach for Eigen most of the time these days).